Apple Watch SE on Family Set-up using Excessive Data

We have 2 apple watch SE's with cellular set up on a family plan for our kids. One of the watches recently ran up a $50 data overage. How can I see what's using this data? Other help articles that I've read are for Apple Watches that are paired to phones - which is not the case here. When I go to the Watch App > Cellular, I don't see any usage information.

Luckily our service provider Bell gave us a credit for this overage - but they could not tell us what was causing it.

How can I see what's using so much data and fix this issue?